The present invention relates to a machine for opening pistachios by means of the forced opening of the shell halves along the natural opening lines.
The invention concerns a machine comprised of a reservoir containing pistachios, an opening device, and a device for supplying pistachios from the reservoir to the opening device, in which a controlled pressure is exerted on the pistachio, giving rise to its opening along the natural sutures of the shell halves.
The pistachio is a fruit whose greatest commercial value is when it is eaten roasted and salted, but with the halves of the shell open, so that it is easier for the consumer to shell the nut.
Fifty percent of the pistachio harvest opens naturally on the tree, and therefore, once selected, roasted, and salted, they can be marketed directly.
The remainder of the harvest, i.e. the other 50%, consists of closed fruits which, owing specifically to the fact that they are closed, cannot be marketed directly as a snack. They are used to produce pistachio seed by a shelling process, and for other less profitable commercial purposes, which represents a significant loss of the harvest""s commercial value.
Traditionally, pistachios have been opened manually, with the concomitant increase in costs for manpower.
Moreover, mechanical opening of the pistachio has to produce a natural-opening impression, and it therefore has to be limited and along the sutures of the shell halves.
The machine for opening pistachios which the invention proposes solves the abovementioned problem in such a manner that it is possible to open the pistachios by producing an opening similar to that of the open pistachio on the tree in natural form.
To this end, and more specifically, the machine comprises a reservoir containing pistachios, a device for opening pistachios, and a device for supplying pistachios from the reservoir container to the opening device. The reservoir container has means for controlling the arrival of the pistachios at the supply device, and the supply device starts from the reservoir and has means for supplying the pistachios individually to the opening device.
The opening device comprises a rotary shaft which carries coaxial disks equipped at their peripheries with chambers, each of a size for axially accommodating one pistachio. During rotation of the shaft, it is possible, for these chambers to be placed consecutively opposite the supply device and then opposite a breaker piston. Stops are generated during rotation of the shaft at the abovementioned positions in which the chambers are opposite the supply device and the breaker piston.
The reservoir containing the pistachios is located above the opening device. On its inside, the reservoir has two transverse surfaces with a vertical inclination in different directions and located at different heights. An opening is defined between the two surfaces for the metered passage of the pistachios. The lower surface defines the bottom of the reservoir. A chamber is delimited between both surfaces, from which the supply device starts.
The supply device is formed of a tube, with an internal section substantially greater than the maximum transverse section of the pistachios. Via the tube, the pistachios slide under gravity to the opening device. The tube starts from the chamber defined between the two inclined surfaces of the reservoir and has an outer sleeve which can be moved axially over the tube in a reciprocating movement, which causes a vibration which facilitates the entry of the pistachios into the tube. A double-door system retains each pistachio at the exit from the tube and deposits a pistachio in each radial chamber of the opening device. A pneumatic system clears any jams produced by the pistachios inside the tube.
The upper end of the axially movable outer sleeve is bell-mouthed to facilitate entry of the pistachios. A cooperating flexible tongue impedes the entry of pistachios into the tube when the sleeve is in its upper limit position. Provision is made for the upper end of the tube to be cut in oblique section. The location of the flexible tongue coincides with the lower portion of the oblique section.
In order to clear any jams, the machine for opening pistachios has a pneumatic system comprising a pair of orifices, one in the outer sleeve coinciding with a longitudinal groove in the wall of the tube, and the other at the exit from the tube. Via the orifices and the grooves, pressurized air is injected in order to expel a jammed pistachio toward the reservoir container. The pneumatic system is activated by activation of a sensor located in the opening device which detects that the radial opening chamber is empty.